Nanoscale materials science and application of nanotechnology calls for more efficient, reproducible and innovative technologies to synthesize novel multifunctional materials, structures and devices. Many potential applications of nanomaterials have been proposed with the expectation that novel physiochemical properties can be achieved in nanomaterials through the manipulation of material size and/or shape, and through the introduction of artificial interfaces and surface chemistry. Current practical applications of nanomaterials may be limited to thin film based devices or isotropic nanoparticles. Traditional top-down micro- and nanofabrication technologies provide the dimensional and compositional control, but they are often associated with complicated equipment, high cost processing, low yield, and limited versatility in altering material selection and design variations. On the other hand, chemical-based synthesis (oftentimes referred to as bottom-up nanofabrication technology) has the capability of producing large quantity of nanomaterials at low cost and high throughput, and sometimes even with non-spherical complicated geometry; but the control over nanoparticle size, shape, composition and deviation is often very limited.
In contrast, the synthesis of materials and structures utilizing nanoporous templates as disclosed herein offers a cost effective and high yield alternative in producing quasi-one dimensional nanomaterials. For example, when appropriate electrochemical synthesis approaches are developed, composition modulation can be introduced along the nanowire axis to achieve multifunctionalities. Synthesized nanomaterials can be easily released from templates and manipulated for them to become the building blocks for various applications.
Examples of nanoporous templates for nanofabrication include anodic oxidized alumina, nuclear track etched polymers, phase separated diblock copolymers, and mesoporous materials. All of them are single layered membrane containing cylindrical pores. Although recently developed multi-step anodic oxidation techniques indicates the possibility of creating a hierarchy pore structure, control of the pore size and distribution and production of the desired structures remains challenging. Furthermore, selective or partial dissolution of the matrix material remains difficult for further nanomanufacturing needs.
The methods and designs discussed herein make use of layers of materials with different chemical solubility and nuclear track etching characteristics that are put together to produce nanoporous templates with individually controllable nanosized pore diameters and pore distribution that are conceived to be selective to the removal of matrices materials of interest. The use of such templates allows for the cost-effective fabrication of unconventional shaped nanostructures with precise pore size, topography and composition which find useful application in the development of new materials.
Nano-sized functional materials hold great promises in transforming the current clinical methodologies through the development and integration of novel diagnosis technologies, therapeutic methods and targeted treatments. At the moment, nanomaterials used for biomedical applications are limited to spherical nanoparticles. The fabrication of well controlled non-spherical nanomaterials poises significant challenges for conventional synthesis methods including the top-down micro/nano fabrication and bottom-up chemical synthesis approaches. Most of the top-down synthesis methods require complicated lithographic technologies and expensive deposition/etching equipment. The techniques discussed herein have the capability of producing complicated structures with well controlled dimension and composition. They are suitable for medication or device level fabrication with well defined nanostructures. For top-down manufacturing, a change in the structure design often involves complete retooling and extended period of waiting time. Prototyping of nanosize structures are often expensive and time consuming. On the other hand, solution-based chemical synthesis has the capability to generate large number of simple nanostructures in short period of time at low cost, and has been extensively used in nanoparticle synthesis. However control over nanoparticles size, shape and composition is limited and remains to this day a limitation for large scale, industrial applications.
Nanoporous membranes have been extensively used as templates to produce nanostructures in addition to the extensive applications in filtering and substance separation. However, conventional nanoporous templates, such as the anodic oxidized alumina, nuclear track etched polymers, phase separated diblock copolymers, and mesoporous structures, contain cylindrical pores with length, density, distribution and sizes are limited by either intrinsic material properties or specific synthesizing methods. Such constrains on pore geometry and simplex template chemistry significantly limit the geometry nanostructures that can be produced.
The present invention overcomes the above-mentioned limitations to produce nanostructures with a wide variety of shapes and functionalities. Applications of such inventions include but are not limited to the cost-effective fabrication of magnetic nanostructures with controlled size, shape, morphology and composition for the delivery of enhanced NMR/MRI agents with improved biofunctionalities.